Like that between being strong and being a good football player. Having charisma is very helpful in teaching. It can get students to concentrate and to pay attention without really trying. But this can be worthless when the teacher is incompetent, unfocused, unclear, or fails in some other way to get the material across. In that case, students may still remember her or him years later, but they won't remember what was covered in the course. With charisma, it's easier to be a good teacher. But charisma alone does not ensure success.

This depends on the university as well as on your specific interests in this field. You might apply especially to universities that have both: a law school with a real interest in legal theory as well as a philosophy department with strength in philosophy of law, ethics, and political philosophy. Such universities also typically offer a joint JD/PhD program, which may be just right for your interests and would allow you to keep more career options open.

I think Will Kymlicka's Contemporary Political Philosophy is a very good text for beginners. It may be a little harder than what you're looking for, but it's a standard work now, one likely to have influenced the exam and those who mark it. It's broad and covers well the main schools of thought. The same is true to a somewhat lesser extent of Adam Swift's Political Philosophy: A Beginner's Guide for Students and Politicians . Swift is a British author teaching at Oxford.

I think the Cambridge University Press editions are probably best in all three cases, they tend to do very good editions -- both of translated and of originally Anglophone works. Typically, a good indicator is what the best recent secondary literature is using or what top scholars assign in their classes. This information is often easily obtainable through Amazon or the internet generally.

You are right: You can possibly learn more from reading books than by going to college. But then it's also true that you might possibly learn more by going to college than from reading books on your own. The real question is: which path will gain you more, and more important, knowledge and understanding? This question is hard to answer in the abstract -- certainly for me, but also for you. If you choose the solitary reading program: Will you still be motivated to go on six months later? And after a year, will you still have a clear grasp of what you understood in the first month? And if you choose college: Will you get into a good one with lots of bright and interesting peers (in my experience, students tend to learn no less from one another than from their teachers)? And will you be able to find there classes taught by people who are truly engaging and inspiring? Given the uncertainties, I would suggest that you go to college (assuming you have a place for September) and give it...

With the help of a former teacher, perhaps, s/he can write a philosophy essay in an area s/he is most interested in. This essay can serve as a basis for assessing whether s/he really has the talent, preparation, and commitment for graduate training in philosophy. If so, this essay can also serve as a writing sample for applications. But it is probably also important to have at least one reference letter from a professor familiar with the applicant who can explain the special circumstances. It may also help to take another philosophy course or two before applying. This may help in developing a suitable essay topic and also in yielding another good grade and strong letter of recommendation.